Premium
σ M , an ECF RNA polymerase sigma factor of Bacillus subtilis 168, is essential for growth and survival in high concentrations of salt
Author(s) -
Horsburgh Malcolm J.,
Moir Anne
Publication year - 1999
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.1999.01323.x
Subject(s) - sigma factor , biology , bacillus subtilis , rna polymerase , gene , microbiology and biotechnology , transcription (linguistics) , gene expression , mutant , rna , biochemistry , genetics , bacteria , linguistics , philosophy
The Bacillus subtilis 168 genome encodes seven extracytoplasmic function (ECF) RNA polymerase sigma factors of unknown physiological function. The sigM ( yhdM ) gene, encoding an ECF sigma factor σ M , is essential for growth and survival in nutrient broth (NB) containing 1.4 M NaCl. Strains insertionally inactivated in the sigM gene form aberrantly shaped cells, which swell and lyse spontaneously during growth in NB medium containing increased levels (0.35–0.7 M) of a wide range of different salts. The sigM gene was co‐transcribed with the yhdL and yhdK genes with transcription initiating from two promoters, P A and P M . The transcript from P M was not detected in a sigM mutant, indicating that the expression of sigM was positively autoregulated. Expression of sigM was maximal during exponential growth and was increased by 50% in NB medium containing 0.7 M NaCl. The activity of σ M is negatively regulated by the proteins encoded by the yhdL and yhdK genes.